buttstrap

例句：

1. 1. 但腿带子；2. 臀部支撑物；3.
   车辆的
2. 4.
   自行车的
3. 1. The buttstrap on the bike is worn out.
   这辆自行车的后座垫磨损了。
4. 2. She used a buttstrap to support her back during the long ride.
   她在长途骑行时用了一个臀部支撑物来支撑背部。
5. 3. He put his feet up on the buttstrap while waiting for the bus.
   他在等公交车时把脚放在屁股垫上休息。